Description: (Applicant's Description) The Flow Cytometer Laboratory Shared Resource is located in the Cancer Therapy and Research Center and is available to all interested investigators in the cancer center. The facility provides flow cytometric analyses to optimize experimental objectives of the SACI members and supports a wide range of NIH-funded research in both clinical and basic sciences. Our current instrumentation includes a Coulter EPICS ELITE flow cytometry system fitted with one water-cooled 5-Watt argon, coherent 300-S tunable wavelength (including UV) laser and one air-cooled 15 mWatt argon Coherent laser. This instrumentation is equipped with an 80486/33 computer system that not only drives system acquisition and analysis but also operates with MS-DOS software for increased computing versatility. A coulter EPICS Model 753 flow cytometer with dual coherent argon ion lasers and one Coherent tunable dye laser is also available. This instrument is equipped with a CICERO acquisition model and a P6-200 MHV processor and 3.1 Gbyte hard drive with the latest version of Cyclops software. Basic services offered to the San Antonio Cancer Institute consist of immunophenotyping (including leukemia, lymphoma, and HIV patients), DNA content and cell cycle analysis (including apoptosis analysis), and intracellular ion concentrations and membrane potential measurement. Recent instrument upgrades now allow for rapid, sterile cell sorting. Protocols currently under development include simultaneous DNA-RNA-protein content analysis, BrdU analysis of S-phase progression, and cytokine characterization for new immunophenotyping assays.